1. Field of the Invention
The present invention generally relates to an improvement for a slotted rail terminal (SRT) and the slot guards used therewith to enhance the safety performance of the SRT during vehicular impacts along the length of the terminal. Primary purposes of a slot guard are to prevent tearing and failure of the guardrail at the downstream end of the rail slots as well as to assist redirection of vehicle components.
2. Description of the Related Art
SRT devices are described in U.S. Pat. No. 5,407,298 entitled xe2x80x9cSlotted Rail Terminalxe2x80x9d issued Apr. 18, 1995; U.S. Pat. No. 5,547,309 entitled xe2x80x9cThrie-Beam Terminal with Breakaway Post Cable Release,xe2x80x9d issued Aug. 20, 1996; and U.S. Pat. No. 5,503,495 entitled xe2x80x9cThrie-Beam Terminal with Breakaway Post Cable Release,xe2x80x9d issued Apr. 2, 1996. All of these patents have been assigned to the assignee of the present invention, and all of these patents are incorporated herein by reference.
The original SRT utilized slot guards to maintain rail integrity during lateral impacts along the length of the terminal without affecting the buckling of the slotted rail in end-on impacts. One prominent feature of the original slot guard was a welded deflector plate that angled away from the back side of the slot guard and rail near the downstream end of a central slot of the guardrail. The primary purpose of the deflector plate was to prevent the bumper or other portions of the impacting vehicle from extending the slots by pushing the rail out and away from the penetrating vehicle, and helping to redirect the vehicle back into traffic.
While the original design for the slot guard has performed well, improvements are desired that would enhance the impact performance of the SRT system and reduce manufacturing and installation cost. For example, the prior slot guard incorporated a deflector plate that was welded onto the slot guard body. As a result, welding of the deflector has become a necessary step in forming the slot guard, thereby resulting in additional manufacturing costs.
In addition, the deflector portion for the standard slot guard protrudes outwardly from the central section, and the plane of the rail member, at a relatively sharp angle. The deflector portion also extends over only a small portion of the entire length of the slot guard. These features are believed by the inventors to be somewhat inefficient for redirection of vehicular components.
Also, one or more connectors are disposed through the central section of the standard slot guard. The inventors have recognized that the presence of connectors disposed through the central portion presents a potential obstacle that could snag portions of vehicles.
An improved slot guard design would be desirable.
The present invention provides devices and methods that enhance impact performance and reduce manufacturing and installation costs. An improved slot guard is described that has a central section and a pair of wing portions that are angularly disposed with respect to the central portion. The wing portions are folded away from the plane of the central section along lines that are angularly oriented with respect to one another so that the wing portions are wider at one end of the slot guard than at the other end. As a result, the slot guard provides a greater height at one of its ends than at the other end.
In operation, the inventive slot guard provides improved portions that assist in deflecting vehicle components. The deflector surface of the inventive slot guard extends along the entire length of the slot guard. In addition, the deflector surface departs from the plane of the rail member at a much more gentle angle than was the case with previous slot guards.
Apertures for connectors are disposed through each of the wing portions, but not through the central portion. The exemplary slot guard preferably provides an asymmetrical connector pattern and/or conspicuous markings so that the slot guard is not inadvertently installed in a reversed configuration on a guardrail.
Methods for forming the slot guard are also described wherein a blank for a slot guard is cut or stamped out of a sheet of metal. Apertures for the receipt of connectors are cut into the blank, preferably in an asymmetrical pattern. Longitudinal sides of the blank are then bent along non-parallel lines to provide the wing portions.